Sulfided Catalyst for Gasoline Diolefin Hydrogenation
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Solution Overview
Problem
Gasolines from catalytic cracking processes contain high levels of mono-olefins and sulfur, particularly diolefins and mercaptans, which are unstable and require selective hydrogenation to meet environmental standards, but existing catalysts are sensitive to sulfur and prone to catalyst deactivation due to polymer formation.
Innovation Solution
A catalyst composed of Group VIb and non-noble Group VIII metals deposited on a porous support, with specific oxide content, sulfidation rate, and surface density, allowing for joint hydrogenation of diolefins and weighting of mercaptans, facilitating easy elimination and maintaining catalyst stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If selective hydrogenation is applied to diolefins, then diolefin content is reduced and stability is improved, but mono-olefin hydrogenation increases and octane number decreases
Solution Approach 1:
The catalyst employs a hierarchical pore structure with macro-pores (>50 nm) for bulk material transport and micro-pores (5-50 nm) for selective reaction sites. This local differentiation of pore sizes creates distinct functional zones: macro-pores facilitate rapid diffusion of reactants and products, while micro-pores provide confined spaces for selective diolefin hydrogenation, thereby achieving both high stability and high selectivity simultaneously
Solution Approach 2:
The catalyst utilizes a porous support structure with controlled pore size distribution (micro-pores 5-50 nm and macro-pores >50 nm) to enable selective hydrogenation. The porous structure provides high surface area for catalytic activity while the specific pore size range ensures selective access to diolefins, achieving both stability improvement and manufacturing precision
2Productivity
If conventional catalysts are used for hydrogenation, then diolefins are converted, but catalyst deactivation occurs due to polymer formation
Solution Approach 1:
The catalyst is pre-treated with sulfur compounds to form sulfided metal surfaces before contact with diolefins. This preliminary sulfidation creates a stable, polymer-resistant catalyst surface that maintains high diolefin conversion activity while preventing catalyst deactivation by gum formation, thereby ensuring both productivity and reliability
Solution Approach 2:
The invention converts the harmful effect of sulfur (which typically poisons conventional catalysts) into a beneficial protective layer. By deliberately introducing sulfur to form sulfided catalyst surfaces, the process transforms sulfur from a catalyst poison into a protective element that prevents polymer formation and catalyst deactivation, maintaining both high conversion and long-term stability
3Object-affected harmful factors
If sulfur content is reduced to meet environmental standards, then environmental compliance is achieved, but catalyst performance deteriorates due to sulfur poisoning
Solution Approach 1:
The invention inverts the conventional approach to sulfur management. Instead of avoiding sulfur to protect the catalyst, the process deliberately introduces sulfur to form a stable sulfided catalyst surface. This inverted strategy allows the catalyst to tolerate and even require sulfur for optimal performance, enabling effective sulfur removal from gasoline without sacrificing catalyst activity
4Stability of the object's composition
If hydrogenation is applied to remove diolefins, then stability improves, but hydrogen consumption increases
Solution Approach 1:
The hierarchical pore structure creates local reaction environments where diolefins are preferentially converted. The micro-pores (5-50 nm) provide confined spaces that enhance diolefin adsorption and reaction probability, while macro-pores (>50 nm) ensure rapid product desorption. This local differentiation maximizes hydrogen utilization efficiency for diolefin conversion while minimizing unnecessary hydrogen consumption, achieving both stability improvement and reduced substance loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process effectively reduces diolefin and mercaptan content in gasolines, maintaining high octane numbers and extending catalyst life by preventing polymer formation, while enabling efficient sulfur removal and hydrogen consumption optimization.
Implementation Method 1
a catalyst containing at least one metal from the group VIb and at least one non-noble metal from group VIII deposited on a porous support
Implementation Method 2
jointly carry out the hydrogenation of polyunsaturated compounds and more particularly diolefins, as well as the weighting of light sulfur compounds and more particularly mercaptans
Implementation Method 3
deposited on a porous support
Data Source
AI summary
Selective hydrogenation of polyunsaturated compounds to monounsaturated compounds and simultaneous thickening of light saturated sulfur compounds by reaction with unsaturated compounds contained in the gasoline, is claimed, where the process is carried out in the presence of a catalyst comprising at least one metal of the group VIb and at least one non-noble metal of the group VIII deposited on a support in which the oxides of group VIb element amounts to 4-20 wt.%, and the oxides of group VIII amounts to less than 15 wt.%. Selective hydrogenation of polyunsaturated compounds to monounsaturated compounds and simultaneous thickening of light saturated sulfur compounds by reaction with unsaturated compounds contained in the gasoline, is claimed, where the process is carried out in the presence of a catalyst comprising at least one metal of the group VIb and at least one non-noble metal of the group VIII deposited on a support in which the oxides of group VIb element amounts to 4-20 wt.%, the oxides of group VIII amounts to less than 15 wt.%, the sulfuration rate of the metal components present in the catalyst is at least 60%, the molar ratio between the group VIII non-noble metals and group VIb metals is 0.6-3 mol/mol, and the density of the group VIb elements per unit of catalyst surface is strictly less than 10 -> 3> g of oxides of group VIb elements per m 2> of the catalyst.